1. Field of the Invention
This invention pertains to the preparation of higher molecular weight aliphatic ketones and more particularly to the catalytic cross-aldol condensation of aldehydes or primary alcohols and ketones or secondary alcohols. The catalyst also catalyzes the aldol condensation of the same or different ketones to produce higher molecular weight ketones.
2. Prior Art
A general review on the technology applicable to the manufacturing a higher molecular weight ketones is found in the article [Ketones by A. J. Papa and P. D. Sherman, Jr., in the third edition, Volume 13, pages 894-941 of Kirk-Othmer: Encyclopedia of Chemical Technology (John wiley and Sons, Inc.).
U.S. Pat. No. 3,890,390 describes the non-catalytic coupling of olefins such as 1-butene to acetone to give methyl ketones such as MAK at elevated temperatures (300.degree. to 650.degree. C.) and pressures (300 to 1500 psi). This process is energy intensive.
Zirconium on various supports is utilized most usefully at temperatures greater than 300.degree. C. to produce higher molecular weight ketones via decarboxylation of aldehydes or their mixtures (U.S. Pat. No. 3,966,822). In a similar process U.S. Pat. No. 1,194,058 teaches that a saturated aliphatic aldehyde and a saturated monocarboxylic acid can react in the vapor phase over a manganese oxide on alumina catalyst to produce higher molecular weight ketones.
Ipatieff [J. Org. Chem., 7, 189-98 (1942)] has shown that copper-alumina and copper-zinc oxide alumina are simultaneously active for dehydrogenation and dehydration. The alcohols used are primary and secondary alcohols. In the case of the primary alcohols it is necessary to work at temperatures of the order of 300.degree. to 350.degree. C.
GB Pat. No. 1,310,614 divulges that a solid catalyst containing copper, chromium, and metal oxides such as barium, calcium, or zinc catalyze the conversion of ketones or aldehydes to higher molecular weight carbonyl compounds. However, alcohols cannot be fed.
Finally, U.S. Pat. No. 2,725,400 uses copper on alumina as well as copper on zinc alumina to catalyze the conversion of alcohols and/or ketones to higher molecular weight ketones. The preferred catalyst is a copper on zinc alumina; whereas, the preferred feed is secondary alcohols as well as ketones derived from them. Relatively high temperatures (greater than 240.degree. C.) and pressures (greater than 175 psi) are required to operate under their conditions.
Methyl Amyl Ketone (MAK), a linear, C.sub.7 ketone, is a high solids coating solvent which has a projected high growth potential by the late 1980's and beyond. A high solids coating solvent allows more resin or polymer to be dissolved/suspended in the solvent. Economic and environmental concerns dictate that the resin to solvent ratio be as high as possible. MAK has the right coating properties and can absorb large amounts of resin/polymer which means smaller amounts of solvent are introduced into the atmosphere and the coating industry uses correspondingly smaller amounts of solvent. MAK is a valued, commercial coating solvent.
It is an object of this invention to provide a method for preparing higher molecular weight ketones.
It is a further object of this invention to provide a facile and economical method for preparing methyl amyl ketone.
Other objects will become apparent to those skilled in the art upon a further reading of the specification.